Automobile crashes into the rear end of trucks and trailers often result in deaths or serious injuries to the automobile occupants. Many such deaths and injuries are due to the impacting automobile underriding the rear end of the trailers or trucks.
While relatively stiff vertical guard members may be extended downwardly from the rear of a trailer to prevent underride, such stiff members, if impacted by an oncoming automobile, result in much of the force being transmitted back to the occupants of the automobile. It is desirable that the energy produced by an automobile impacting the rear of a trailer be absorbed or gradually reduced as the automobile and its occupants are slowed down.
In the past, automobile frontal front elements have been used to provide a controlled energy absorbing crush upon impact.